Observation and Analysis of Microclimate and Evapotranspiration Characteristics of Different Crops Underlying Surfaces in the Loess Plateau in East of Gansu Province

Abstract

The Longdong Loess Plateau is an important rainfed agricultural area in China.It is of great significance to study the differences of land surface processes under different farmland for understanding the regional land-atmosphere interaction.Based on the farmland micrometeorological and lysimeters observation data of Qingyang City， Gansu Province from June 2021 to May 2022， this paper analyzed the differences in microclimate and evapotranspiration characteristics of three different crops： apple， corn， and wheat； combined with correlation analysis and sensitivity analysis， the main influencing factors of evapotranspiration from the underlying surface of different crops were discussed.The results showed that： （1） The temperature and land-air temperature difference in the apple field were smaller during the growing period； the relative humidity of corn field was higher than that of wheat field， especially in the canopy； the surface albedo of corn field was basically lower throughout the year， but it increased in May due to covering with mulch film， and its annual average net radiation was significantly lower than that of the apple field and wheat field； （2） The daily variation of evapotranspiration basically followed the mid-growth stage > the early growth stage > the maturity stage， the evapotranspiration of corn was the largest in the mid-growth period， reaching a maximum of 4.9 mm·d-1， and the annual daily evapotranspiration of wheat field was less than 3 mm·d-1.during the whole growth period， the change of daily evapotranspiration of apple field was the most， while that of wheat field was relatively stable； （3）Net radiation was the main meteorological driving factor for evapotranspiration change in apple field and corn field during the growing period， but it had relatively little effect in wheat field； the sensitivity of evapotranspiration to saturated water vapor pressure difference in the growing period of the three places was smaller than that in the non-growing period.

Keywords

• loess plateau
• agricultural microclimate
• lysimeter
• evapotranspiration
• sensitivity analysis